Sewing machine



July 12, 1955 N. w. COTTRELL 2 SEWING MACHINE Filed Jan 18, 1952 4 Sheets-Sheet l INVENTOR.

NEWTON W. COTTRELL BY July 12, 1955 N. w. COTTRELL 2,712,802

SEWING MACHINE Filed Jan. 18, 1952 4 Sheets-Sheet 2 0' INVENTOR. NEWTON W. COTTRELL LL BY ATTORNEY.

July 12, 1955 N. w. COTTRELL 2,712,802

SEWING MACHINE 4 Sheets-Sheet 3 Filed Jan. 18, 1952 IN V EN TOR.

ATTORNE Y.

J On y 2, 1955 N. w. COTTRELL 2,712,802

SEWING MACHINE Filed Jan. 18, 1952 4 Sheets-Sheet 4 INVENTOR. NEWTON W. COTTRELL ATTORNEY.

United States PatentO SEWING MACHHNE Newton W. Cottreii, South Bend, Ind., assignmto Union Special Machine Compan Chicago, 111., a corporation of Illinois Application January 18, 1952, Serial No. 267,179

6 Claims. (Cl. 112-184) This invention relates to sewing machines and more particularly to a thread guard for use in a lock-stitch machine of the general type having one or more threaded needles movable through the Work and a feed dog which reciprocates with the needle in the line of feed, and a rotary hook cooperating with each needle supported to turn on a vertical axis. It relates especially to a machine of this character in which the needles are oscillated in the line of feed to assist in advancing the work.

The invention is herein disclosed in a preferred form as embodied in a two-needle, needle feed, lock-stitch machine which is in many respects similar to that illustrated in the patent to Quist No. 2,329,484, dated September 14, 1943. In this machine the two needles are moved with the feed dog in the line of feed to assist in feeding the work, and two rotary hooks are disposed one at each side of the needle group and are arranged to rotate in the same clockwise direction about vertical axes. With this arrangement of the needles and rotary hooks, one of the books is arranged to engage and draw a loop of direction of feed. ranged to operate at a recommended maximum speed of about 4,000 stitches per minute and, since the hooks are each needle reciprocation, each a speed of about 8,000 revolu- At this speed of operation, difiiculty has been encountered with breakage of the needle thread associated with the right hand needle and its cooperating rotary hook which seizes the loop from the needle and throws it rearwardly in the direction of feed. It has been found that the breakage referred to is caused by the unspeed by the book as drawn around the thread casing. The upper leg of the thread loop is frequently caught on the rear corner of the work engaging surface of the feed dog. Then as the thread is suddenly taken up by the take-up devices, after the loop has been carried half way around the bobbin case, it is drawn across and against the relatively sharp edge of the engaged tooth of the feed dog and is severed thereby.

It is a primary object of the present invention to provide a novel and improved construction and arrangement of the feed dog which, in relation to its associated rotary hook, will positively control and confine the needle loop, as it is drawn by the rotary hook at high speeds, to avoid engagement of the thread with the toothed or serrated work engaging surface of the feed dog and thus prevent cutting or breaking of the thread.

With this and other objects in view as may hereinafter appear, a feature of the invention consists in the improved construction and arrangement of the feed dog associated with the rotary hook which takes its needle loop from the needle rearwardly in the direction of feed;

' through 2,712,802 Patented July 12, 1955 said dog having formed on the underside and at the rear edge of the laterally extending serrated cloth engaging portion thereof a downwardly projecting lug, which acts to confine and to direct the needle thread loop, that is formed at the beginning of the upward movement of the needle for seizure by the rotary hook, in a path away from and substantially below the level of the cloth engaging surface of the feed dog.

Other objects and corresponding advantages of my invention will appear from the following detailed description of the drawings, in which:

Fig. 1 is a detail view, in vertical section, taken transversely of the line of feed through the axis of the vertical hook unit looking toward the rear of the machine, illustrating particularly the arrangement of the needles, feed dog and the right hand rotary hook assembly, including the hook which takes its loop from the needle while traveling rearwardly in the direction of feed;

Fig. 2 is a plan view of the machine but with the cover plates removed to illustrate particularly the arrangement of the feed dog and cooperating rotary hook assemblies;

Fig. 3 is a bottom plan view of the throat plate of the machine shown in Fig. 2;

Fig. 4 is a bottom plan view of the machine base, illustrating particularly the rotary hook and feed dog actuating mechanisms;

Fig. 5 is a vertical sectional View, taken substantially along the line 5-5 of Fig. 2, illustrating particularly the feed dog and the actuating mechanism therefor largely in elevation;

Figs. 6 and 7 are isometric views on an enlarged scale of the feed dog as seen from different angle Fig. 8 is a detail view in front elevation, on the scale of Fig. 5, of the feed dog and needle guard associated therewith;

Fig. 9 is a View in right side elevation of the feed dog and needle guard assembly shown in Fig. 8; and

Fig. 10 is an isometric view of the needle guard on a somewhat larger scale. Referring specifically to the drawings in which only so much of the machine is shown as is believed necessary to illustrate the connection of the present invention therewith, the machine comprises two needles 20 and 22, Fig. 1, which operate in unison and are passed downwardly apertures formed in a feed dog 24 which is given a four-motion movement with respect to a stationary throat plate 26. Separate work engaging portions of the feed dog pass upwardly through openings 26a and 26b in the throat plate. Two rotary hooks 28 and 30 are provided slightly beneath the plane of the under face of the throat plate, these being supported to turn on vertical axes and arranged respectively at the left and right of the feed dog assembly to cooperate with the needles 20 and 22, respectively. In accordance with the disclosure of the patent to Quist above referred to, the work is preferably advanced by the cooperative movement of the needles and feed dog which are moved'forward and back in the line' of feed. The rotary hooks are driven in unison in a clockwise direction, as shown in Fig. 2, at a two-to-one ratio with the needle reciprocation. The rotary hooks 28 acts to take the loop 21 of needle thread from the needle 20 as the loop seizing beak of the hook is moving forwardly in a direction opposed to that of .the work feed. The rotary book 30 rotated in the same its loop 23 of needle thread from the needle 22 while the needle seizing beak of this hook is moving rea'rwardly in the direction of Work feed; (I; will be understood that this seizing of the needle loops takes place as the needle threads are slack and bowed outwardly by'the slight upward movement of the needles. A portion of the machine base, including the driving connections for the feed dog'and rotary hooks,.-isshown derstood that the ventional hook opener If desired the spring 3 j in the drawings and comprises providing a work supporting mounted the throat plate 26 held in place by screws 36. The drivingconnections including a horizontally disposed drive shaft 38 which projects from a gear housing 40, generally indicated in Fig. 4, that is supported along its length by suitable bearing lugs 42 and 44. It will be unshaft 38 may be driven, through suitable gearing, from a main driving shaft in the overhanging arm of themachine, as shown in said patent to Quist. A rock shaft 46 is mounted in the base, in parallel relation to shaft 38, and is driven from the upper main shaft by I ama soa;

a framework 32, Fig. 4, I, plate 34, on which is connections similar to those disclosed in said Quist patent.

It is supported toward its outer end in bearing lugs 48 and 50 carried by the framework 32. The rotarylhooks 28 and are continuously driven from the shaft 38 by means of two identical spiral gears 52 and 54 secured to said shaft, Spiral gear 54 meshes with a spiral gear 56, Fig. 1, carried on a vertically disposed shaft 58 in the hook unitfrom which is driven the rotary hook 30. It willbe understood that hook unit 28 is of opposite hand but is driven in the same manner and is of substantially the same construction.

Inasmuch as the driving and supporting assemblies for each of the rotary hooks 28' and 30 identical, the supporting and driving assemblyfor the hook 30 only will be described. As shown in Fig. l, the vertically. disposed drive shaft 58 is mounted within a pair of bushed bearings 60, 62 carried by a bracket 64 suitably secured to the base of the machine. Within the rotating component of the hook, at the upper end of the assembly, is mounted the usual thread case 66 (Fig. 2) which is held in position axially within the rotary component of thehook by the usual rib and groove construc tion and is prevented from rotating by cooperation 'of a projection 67 with a notch 67a in the underface of the throat plate. A bobbin 68 carrying the stitch locking thread is mounted on a spindle at the center of the threadcase and is retained therein by 'a spring arm 6841. Conmeans are provided for shifting the thread case in a counterclockwise direction *at the appropriate time in a s 'tch forming cycle to facilitate passage of the needle thread between the cooperating faces of the projection 67 and the notch 67a. This comprises a finger 70 adjustably mounted on an arm 72 secured to.

.a rock shaft 74 that is rocked at an appropriatetimein the cycle.- The free end of the finger 70 cooperates with a projection 76 of the thread case to accomplish the indicated purpose. As the needle loop'23 is carried around 'thethread case by the rotary component of the hook it incorporates within the loop a portion of .the stitch locking thread 69 supplied from the bobbin 68.-

bobbin thread is drawn from the bobbin under a suitable tension that is provided in one or both of two ways. 7 a suitable aperture in'the thread case and then passes a slight distance circumferentially of the outer face of the thread case beneath a spring element 71. The outer end of this element is bent inwardly through'an opening 66a in the thread case and is provided with a finger 71a that is extended upwardly. into a position in which it bears upon the periphery of the upper disk'or flange of the bobbin 68. Projection 76 of the'thread caseis notched at 76a to accommodate the upper end of the finger 71a. By means of the usual adjustment screw 71b.the' friction force upon the bobbin provided by the finger 71a at. the

,endof'the spring element 71 may be varied as desired to provide an appropriate braking action for the bobbin. I 7 element 71 may also impartdirect frictional resistance to the bobbin thread as it passes between the element and the outer face of the thread case.

-: As generally indicated in Fig. 1, lubrication of the hook assembly is effected core pin 78 mounted within an axial bore in drive shaft the hook are substantially It passes outwardly through by means of a spirally grooved 'core pin and the bore of the hook present invention, no further description or illustration thereof is believed necessary.

The feed dog 24 of the illustrated construction, as best shown in Figs. 6 and 7, comprises a body portion which extends obliquely upwardly and forwardly in the direction of feed and is formed with two spaced, toothed, cloth engaging portions 83 and that are separated by a slot 92. These toothed portions of the dog are flanged outwardly from the body'portion of the feed dog 24. The flanged cloth engaging portions feed dog are provided, respectively, with needle receiving apertures 94 and 96 through which the needles are passed into cooperating'relation with the respective hooks during each reciprocation of the needles. The toothed cloth engaging portions 88 and 90 of the feed'dog 24 are constructed and arranged to pass upwardly through the slots 26b and 2611, respectively, provided in the throat plate 26.

.The feed dog 24 is formed with a downwardly extending shank portion 98 which is secured to a vertically extending portion of a horizontally disposed feed-bar 190 that i s,in turn, supported andactuated to impart a four-motion feeding movement to the feed dog. As best shown in Fig. 5, the feed-bar 100 is pivotally connected at its forward end to a strap 102 carried on an eccentric 104 on the drive shaft 38.v At its rear end the feed-bar 100 is pivotally connected with an upstanding feed'rocker 106 carried by the rock shaft 46. Reference may be had to said Quist patent for further details as to the feed-bar actuating means.

Itrwillbeunderstood that the motion imparted to the feed dog by the connections above referred to are syn chronized with the needle actuating mechanism, not specifically illustrated,.to cause in a forward and back direction with the needles, the downward and forward movements of the feed dog taking place while the needles are withdrawn from the work and ,while the hooks are engaged in drawing the needle thread loops around the respective thread cases 66.

a An important feature of the present invention consistsin the provision on the feed-dog of positively'acting v means for' controlling the feed dog. In the operation of the machine'it appears that the needle thread engaged by the rapidly moving rotary hook, is .balloonedoutwardly and upwardly at the same time that the feed dog moves downwardly and in the return direction opposed to the direction oi travel of the hook beak. These relative movements of the hook and feed dog, as the needle loop is drawn rear wardly by the hook, taken in connection with the fact that the feed dog at this time occupies one of its lowest positions with relation to the work support, causes the upper leg of the needle loop to be'brought into engagement with the toothed rear edge of the surface'90 of the feed dog, particularly at the corner indicated at 108 in Figs. 6 and 7, when the special guard means of'the present invention are not provided. Whenever the needle loop is thus caught on the corner of the feed dog, the thread is subjected to wear and a severe strain as the loop is quickly drawn from thethread case by the usual take-up devices. This occurs 88 and 90 of the downwardly extending eccentric the feed dog 24 to move 75 after the loop has-passed 58, oil being forced upwardly through the slightly more than half way around the thread case and is drawn up by the take-up means to form and tighten the stitch. Breakage frequently occurs as the part of the loop engaged with the feed dog is suddenly pulled tight.

To confine the thread within closer limits and to direct the ballooning tendency thereof away from the upper edge of the feed dog 24, a lug 110 is formed on the underside or" the flanged portion 90, this lug extending transversely along the rear edge of the portion 90 and beneath the corner designated at 108. The needle thread when engaged by the hook beak now travels from the underside of the aperture 96 in the work engaging sur face 90 around or beneath the lug 110 and thence to the hook along the horizontal path shown in Fig. 1, thus eliminating any tendency of the thread to balloon upwardly, and at the same time causing the thread to be positively retained in a position substantially below the level of the rear corner 108 of the work engaging surface. No comparable difiiculty has been encountered in the operation of the left hand rotary hook 28, due to the fact that the needle thread loop for this hook is carried forwardly by the beak of this hook as the loop is seized. The distance from the needle opening 94 to the forward end of the part 88 of the feed-dog appears to be great enough to prevent catching of the needle thread loop on the forward corner of part 88. However, a cor-- responding needle loop guard may be provided, if de sired, on the flanged portion 88 of the feed-dog. It will be understood that, if this is done, a lug similar to the lug 118 will be applied to the forward underedge of the outwardly flanged portion 88 of the feed dog, which would similarly control the ballooning of the thread loop taken by the beak of hook 28.

The illustrated machine is further provided with an improved needle guard generally designated at 112. This needle guard is channeled at 114 to fit snugly against the underedge of the inclined body portion of the feed dog 24 to which it is secured, and is provided with a forwardly extending Wedge-shaped projection 116 which is located between the paths of the two needles 20, 22 and acts to prevent lateral displacement of the needles to ward one another, and to insure the correct positioning of the needles with relation to the beaks of the hooks for the seizing of the needle thread loops. As shown at 118, each face of the body portion of the feed-dog is provided with a concave recess to supply the needles and their threads as the needles pass through the openings 94 and 96 into cooperation with the hooks.

it will be understood that the machine embodying the foregoing improvements will be provided with the customary mechanisms and adjuncts to be found in machines of the character disclosed to render the same capable of functionin properly. Thus, mechanism of the type disclosed in said Quist patent will be provided to impart the up and down movements of the needles and to impart the desired needle-feed movements thereto along the line of feed. All of the operative devices of the machine which serve to form the lock stitches and to advance the work are driven in coordinated relation by suitable connections from the main driving shaft which preferably extends longitudinally of the overhanging arm of the machine and is driven through the usual combined handwheel and pulley. For further details as to the construction and operation of the machine as a whole, reference may be had to the application of Norman V. Christensen, Serial No. 695,426, filed September 7, 1946, and the patent to Sauer No. 2,386,349, granted October 9, 1945.

While a preferred embodiment of the invention in a sewing machine has been described in some detail, it :ill be understood that various changes may be made in the construction and arrangement of the several parts within the scope of the appended claims.

What is claimed is:

1. In a needle feed lockstitch sewing machine having a machine frame including a work supporting surface,

adequate clearance for I a thread carrying needle reciprocable through the work supporting surface, a feed dog having a four-motion feed and return movement, said feed dog being formed with a supporting shank and a toothed work engaging portion extending laterally from said shank and longitudinally in the direction of feed and apertured to receive the needle, a vertical axis rotary hook disposed beneath the work supporting surface at one side of the line of feed rotating in a direction to seize and to throw a loop of needle thread from the needle rearwardly in the direction of feed in the region of said work engaging portion of the feed dog, and means for confining the needle loop drawn rearwardly from the needle by the hook which comprises a downwardly projecting thread engaging lug formed on the underside of the work engaging portion of the feed dog in rear of the needle receiving aperture therein and in the path of movement of said needle thread loop.

2. In a needle feed lockstitch sewing machine having a machine frame including a Work supporting surface, a thread carrying needle reciprocable through said work supporting surface, a vertical axis rotary hook disposed below the work supporting surface rotating in a direction to seize and to throw a loop of needle thread from the needle rearwardly in the direction of feed, and a feed supporting shank and a toothed outwardly flanged work engaging portion extending longitudinally in the direction of feed and apertured to receive the needle, means for rotating the hook to cause it to seize the needle thread loop and carry it rearwardly beneath said work engaging portion of the feed dog, means imparting a four-motion feed and return movement to the dog synchronized with the movement of said hook, and means for confining a needle loop drawn rearwardly in the direction of feed from the needle by the associated book which comprises a downwardly projecting thread engaging lug formed on the underside of and adjacent the rear edge of the associated outwardly flanged portion of the feed dog in the path of movement of the needle thread loop.

3. In a needle feed lockstitch sewing machine having a machine frame including a work supporting surface, a thread carrying needle reciprocable through the work and longitudinally 1n the line of work feed and apertured to receive the needle, means for rotating the hook and for imparting a four-motion feed and return movement on the underside of and adjacent the end of said work engaging portion toward which the loop is drawn from the needle and thrown.

4. In a two-needle, needle feed lockstitch sewing machine having a machine frame including a work supporthooks, each of said hooks being arranged to seize a loop of needle thread from one of said needles and throw the same in a direction along the line of feed, one of said hooks serving to throw its needle loop in the direction of feed, and means for confining the receive the associated needle, hooks and actuating the feed a of said hooks being arranged to seize a loop of needle 7 needle loop thrown in the direction of feed from one of said needles by the associated hook which comprises a downwardly projecting thread engaging lug having a rounded lower edge and formed on the underside of the flanged portion of the feed dogtions associated with the two needles and extendingilatorally from said shank and longitudinally in the direction of feed, each of said portions being apertured to thread from one of said needles and throwthe same in a direction along the line of feed, one of said hooks servingto throw its needle loop in the direction of feed, and

means for confining needle loop thrown by said one of said hooks from the associated needle which comprises a downwardly projecting thread engaging lug formed on means for rotating the dog in timed relation, each a loop of needle thread from 8 the underside of and at that end of the associated work engaging portion of the feed dog toward which the needle loop is thrown by the hook and disposed in the path of the loop so thrown.

6. Ina needle feed lockstitch sewing machine having a machine frame including a work supporting surface, a

thread carrying needle reciprocable through the work supporting surface, a feed dog having a four-motion feed and return movement,

said feed dog being formed with a supporting shank and a toothed work engaging portion extending laterally from said shank and longitudinally in the direction of feed and apertured to receive the needle, a vertical axis rotary hook disposed beneath the work supporting surface at one side of the said feed dog, means for rotating said hook in a direction to seize and to throw the needle rearwardly in the direction of feed, and guard means disposed in the path of said needle loop and associated with said feed-dog at the underside of said work engaging portion for confining the needle loop as it is thrown rearwardlytrom the needle by the hook and directing it away from the toothed upper surface at the rearward end of said portion.

References Cited in the file of this patent UNITED STATES PATENTS 2,329,484 Quist Sept. 14, 1943 

